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Ashok Silwal, a doctoral candidate and graduate research assistant at 麻豆精品视频 (麻豆精品视频), a part of the University of Alabama System, has been chosen to receive a NASA Future Investigators in鈥疦ASA鈥疎arth and Space Science and Technology (FINESST) scholarship to study stream interaction regions (SIRs) in the heliosphere. SIRs accelerate energetic particles, impacting the interaction between the solar wind and the Earth鈥檚 magnetosphere. How energetic particles are generated in the solar wind is a fundamental question in heliophysics. FINESST awards are research grants for up to three years and $50,000 per year.

鈥淪IRs are very large-scale structures formed by the interaction between two different solar wind streams 鈥� usually as a faster stream catches up with a slower stream from behind,鈥� Silwal explains. 鈥淎s the structure rotates with the sun at the solar spin speed, it is frequently referred to as 鈥榗orotating鈥� interaction regions (CIRs). Energetic particles are often observed at or near SIRs and are a part of what we call space weather 鈥� conditions in space that can impact satellites, astronauts and even technology on Earth, such as GPS systems and power grids. How these particles are generated is still an open question, despite many theories being proposed.鈥�

Ashok Silwal, a third-year doctoral candidate and graduate research assistant of Space Science at 麻豆精品视频 studying solar turbulence and energetic particles.

Courtesy Ashok Silwal

鈥淏eing selected for this FINESST award is a testament to Ashok鈥檚 accomplishments,鈥� says Dr. Lingling Zhao, an assistant professor in the 麻豆精品视频 Department of Space Science and Silwal鈥檚 advisor. 鈥淗is proposal details some important scientific questions about turbulence and energetic particles in the SIRs. For example, how does turbulence near the SIRs differ from the quiet solar wind? What are the physical mechanisms that produce energetic particles? And what is the role of turbulence in accelerating particles? I鈥檓 confident this project will yield highly valuable results for the scientific community.鈥�

SIRs tend to dominate large-scale solar wind dynamics, and the interaction of SIRs with the magnetosphere causes most geomagnetic storms during the minimum of the solar cycle.

鈥淢y specific research is the connection between turbulence and energetic particles,鈥� Silwal says. 鈥淭丑别 solar wind is naturally embedded with turbulence, but what鈥檚 more interesting is how turbulence is processed by the SIRs. Using data measured by spacecraft, we can observe how properties of turbulence change in different parts of SIR structure. These changes can then be correlated to variations in the measured energetic particle intensity. I鈥檝e found that, for SIR-accelerated particles, the increase in turbulence amplitude within the SIR may be an important factor.鈥�

Most existing knowledge of SIRs comes from single point observations near the Earth, but data from different locations are now available, thanks to recent missions such as and

鈥淲hat is special about this project is the emphasis on multi-point observations,鈥� Dr. Zhao notes. 鈥淧arker Solar Probe and Solar Orbiter have provided new insights by measuring fields and particles at different locations within Earth's orbit around the sun. By comparing data from the new missions with other data measured near Earth, Ashok's project will be able to address how fast and slow solar wind stream interactions affect turbulence and energetic particles.鈥�

鈥淪ince SIRs are large-scale structures, having multiple vantage points is extremely valuable,鈥� Silwal adds. 鈥淲hat鈥檚 interesting about them is that they are always present in the solar wind, unlike other more transient phenomena like solar flares. And since they corotate with the sun, the same SIR structure can sweep by the Earth repeatedly every month or so. Therefore, SIRs can be especially important during solar minimum when solar activities are weak. In this work we鈥檒l also learn more about the physical mechanisms that accelerate particles and try to understand which mechanism(s) is consistent with observational results.鈥�

鈥淭丑别 solicits proposals from accredited U.S. universities and other eligible organizations for graduate student-designed and performed research projects that contribute to the Science Mission Directorate鈥檚 science, technology and exploration goals.